After cuda9.2 installed, got error when run nobody sample

Accelerated Computing CUDA CUDA Setup and Installation
5

@txbob thanks for the hint! You set me on the right track. This took the better part of an afternoon to solve and I’ll document here in case it helps the others.

I’m not on a laptop nor do I have multiple GPUs. But this was the initial result from running glxinfo | grep -i opengl:

OpenGL vendor string: VMware, Inc.
OpenGL renderer string: Gallium 0.4 on llvmpipe

Ok so OpenGL was clearly not using my GPU. There were several threads on the Ubuntu launchpad forums for this:

But none of these solved my problem. I then checked my ‘/var/log/Xorg.0.log’ and found this issue:

[    47.013] (EE) NVIDIA(0): Failed to initialize the GLX module; please check in your X
[    47.013] (EE) NVIDIA(0):     log file that the GLX module has been loaded in your X
[    47.013] (EE) NVIDIA(0):     server, and that the module is the NVIDIA GLX module.  If
[    47.013] (EE) NVIDIA(0):     you continue to encounter problems, Please try
[    47.013] (EE) NVIDIA(0):     reinstalling the NVIDIA driver.

and this:

[    46.743] (II) LoadModule: "glx"
[    46.820] (II) Loading /usr/lib/xorg/modules/extensions/libglx.so
[    46.823] (II) Module glx: vendor="X.Org Foundation"
[    46.823] 	compiled for 1.19.6, module version = 1.0.0
[    46.823] 	ABI class: X.Org Server Extension, version 10.0

which led me this thread:

https://devtalk.nvidia.com/default/topic/830711/linux/failed-to-initialize-the-glx-module-please-check-in-your-x-log-file-that-the-glx-module-has-been-lo/

Long story short, the X server was loading /usr/lib/xorg/modules/extensions/libglx.soinstead of /usr/lib/nvidia-396/xorg/libglx.so.

Per the thread, I backed up and replaced the Xorg version with a symlink to the nvidia version:

sudo mv /usr/lib/xorg/modules/extensions/libglx.so /usr/lib/xorg/modules/extensions/libglx.so.bac

sudo ln -s /usr/lib/nvidia-396/xorg/libglx.so /usr/lib/xorg/modules/extensions/libglx.so

I then rebooted, ran glxinfo | grep -i opengl again, and got the correct values this time:

OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce GTX 750 Ti/PCIe/SSE2
OpenGL core profile version string: 4.6.0 NVIDIA 396.26

and now Mandelbrot, nbody, simpleGL etc are all working beautifully.

Wonderful afternoon of yak shaving…hope this helps someone :p